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Surface alloying is necessary to enhance the surface features of machine elements. In the present study,
feasibility of micro-electric discharge machining (micro-EDM) process for surface alloying has been
investigated. Experiments are conducted on Nickel sheets using tool of Ti6Al4V with EDM oil and
kerosene as dielectric. The surface modification...
Context in source publication
Context 1
... intensifies penetration into base metal and recast layer thickness increases. [40] Similarly, on increasing frequency and keeping pulse-on time constant, more amount of heat is transferred to both the electrodes which cause increase in recast layer thickness. [41] Transverse section of a machined sample exhibiting recast layer has been shown in Fig. 8. FESEM images of cross section of samples has been shown in Figs. 9 and 10. Two distinct phenomena were observed, i.e., there was more material removal than addition with irregular surface formation, uniform layer with material addition. Former was observed at higher values of parameters, due to big crater formation over workpiece and ...
Citations
... EDM process. Note: EDM, electrical discharge machining[13]. ...
... Current is most dominant parameters in EDD which created uniform deposition over the surface. SR drastically increased with increasing of discharge current [22]. At higher range of current, strength of the discharge spark was too high that eroded both workpiece and electrode materials. ...
Electrical discharge deposition (EDD) is surface modification method, used to produce thin and thick coating layer on the workpiece materials. Light weight alloys are used to manufacture the components are used in automobile, aircraft and medical applications. Nowadays, Mg alloys surface are modified with desired coating based on the application. However, it cannot be applied in the high load sliding applications due to its poor wear resistance. Hence, it is essential to improve the wear resistance in order to employ in the high load sliding conditions. In this investigation, AZ31B Mg alloy is coated using EDD with WC-Cu powder compacted electrode. Response surface methodology is applied to conduct the experiments and develop the empirical model. Selected factors are compaction load, discharge current and pulse on time while coating thickness (CT) and surface roughness (SR) are measured as responses. Higher discharge current and pulse on time with low loaded electrode increases CT and SR. Conversely, lower setting of current and pulse on time with high loaded electrode reduces the CT and SR. Lump coating with numerous micro cracks were observed at the surface coated using low loaded electrode (150 MPa), resulted increased SR. Maximum layer thickness of 120.55 µm was successfully achieved at compaction load of 150 MPa, current of 4A and pulse on time of 90 µs. Minimum coating thickness of 98.76 µm was observed at compaction load of 200 MPa, current of 2A and pulse on time of 50 µs. Uniform deposition with small sized globules were observed at the surface coated using high loaded electrode (200 MPa) that reduced SR. Energy dispersive spectroscope and scanning electron microscope analysis were carried out to study the quantity of elements and microstructure of the coated surface respectively.
... Figure 6 shows traces of burning and recast material, micro-hole or crater-like structures formed on the workpiece surface [31]. These structures are encountered in the recast layer (white layer) , which is a typical result of the electro-erosion process [32]. The recast layer is a hard-brittle structure, the thickness of which varies according to the melting point of the electrode, discharge energy and pulse off time [33]. ...
Aluminum alloys are widely preferred in various fields such as aerospace, ship and automotive due to their lightness and relevant production cost. In this study, electro discharge technique was used in the processing of aluminum 5083 alloy (Al5083) produced by powder metallurgy method. The surface quality resulting from the experiments was investigated in terms of Ra, Rz and Rsm. Experimental studies were carried out according to Taguchi L9 orthogonal experimental design, using three different levels of discharge current, pulse on time and pulse off time parameters. As the discharge current increased, Ra and Rz increased, Rsm first decreased and then increased. As the pulse on time increased, Ra and Rz first increased and then decreased, and Rsm increased. When the pulse off time increased, Ra and Rz decreased and Rsm increased. As a result of the analysis of variance (ANOVA) performed to determine the effect rates of the variable parameters on the surface quality, the order of importance of the parameters was found to be discharge current, pulse off time and pulse on time. The effect of discharge current, which is the most effective parameter according to ANOVA, on Ra, Rz and Rsm was calculated as respectively 70.87%, 70.41% and 36.34%. Microscopic images taken from the tool (copper) and workpiece surface show that the craters and peaks formed by the spark effect are formed on both material surfaces.
... The working principle of the EDM technique relies on the theory of electrical erosion. In this technique, materials are removed from the workpiece by creating a series of discrete electrical sparks (with a very high-frequency range of 10 3 À10 6 Hz [23]) between the cathodic tool electrode and the anodized conductive workpiece. Both the electrode and workpiece are separated by a tiny gap and are dipped within a dielectric fluidic medium such as dielectric oil, deionized (DI) water, or kerosene [24,25]. ...
Shape-memory alloys (SMAs) have received a great deal of interest due to their excellent properties, which make them significant for various applications. Despite its unique properties, the processing of these alloys is often challenging as it endures a solid-state transition. This chapter thus aims to explore non-conventional machining techniques such as laser beam machining (LBM), electrical discharge machining (EDM) and its associated techniques for the processing of these alloys without altering their intrinsic properties. Both the techniques are discussed in terms of their working mechanism and contribution to the processing of SMA alloys. In addition, the use of EDM processed SMA alloys in various actuators, in particular micromanipulator, micro-positioning stage and tunable coil, is also discussed. Finally, it concludes by discussing the main outcomes of the chapter.
... Application of EDM to titanium and its alloys allows not only to shape variety of holes (irregular, deep, blind, small etc.) but also enables surface modification (i.e. texturing [19], alloying [20] or surface hardness improvement [21]) or producing hard and solid-lubricating over titanium alloy [22]. In [23] the influence of electrode material and electrode polarity was investigated and this work was focus on the dimensional accuracy of EDMed Ti6Al4V parts. ...
The paper focus on the importance of heat treatment procedure of Ti10V2Fe3A alloy for the removal process during EDM. The goal of the research was to analyse the influence of Ti10V2Fe3Al alloy microstructure on the surface integrity after electrodischarge machining (EDM). By varying the time and temperature of the heat treatment operation the samples with various morphologies and a volume fraction of the α phase have been obtained. Then, all the samples were electrodischarge machined in sinking kinematics. The results analysis focuses on the microstructural changes, microhardness and geometrical properties of the machined surface. In the surface layer cross-section typical zones differing in chemical composition, microstructure and microhardness between samples with different initial morphologies and a volume fraction of the α phase were distinguished. Also significant differences in 3D surface roughness parameters such as Sa, Sz, Sq, Sk, obtained for each investigated sample after EDM were detected. Observed changes in surface layer corresponds to the temperature of heat treatment and annealing time and the resulting volume fraction of the α phase.
... The modification of surface can be carried out in different ways e.g. recast layer formation during machining process [11], by using green compact powder electrodes [12], or by using powder mixed dielectric medium [13]. The conventional EDM is not suitable for the miniaturised components mainly due to high discharge energy. ...
... The dielectric absorbs around 80% of the spark energy produced by the sparks whereas the remaining 20% is distributed between the two electrodes [11]. During the micro EDM process, due to the electrical sparks, material of the electrodes and the suspended particles melts simultaneously. ...
This work aims to produce a hard and solid-lubricating layer over Ti6Al4V work piece surface through μ-EDM process. Deionised water mixed with tungsten disulphide (WS2) powder (average particle size: 15 μm) was used as dielectric medium and brass rod of diameter 800 μm was used as the tool. Various responses such as micro-hardness (HV), recast layer thickness (RLT), material deposition rate (MDR), and surface roughness (SR) were measured and correlated with FESEM images, EDS, XRD and EPMA results. The results indicated the formation of various intermetallic compounds on the modified surface. A higher MDR (0.049 mm3/min) was found at maximum powder content of 12 g/L. There is an improvement in micro-hardness from 421.38 HV to 881.34 HV when compared to that of the base material (417.61 HV). Maximum recast layer thickness of 13.11 μm was obtained at parameter settings of 12 g/L, 60 V and 70% duty factor. Wear test was performed and found that the specific wear rate is decreased as compared to that of the base material.
... The hardness strength and reduction in the carbon layer thickness are very much important in the EDC process parameters selection, while the hardness values are almost uniform throughout the top surface which was produced by higher pulse of time. The hardness value varies according to the depth that shows the layer generation and deposition of alloying elements for improved wear resistance [15][16][17][18][19]. ...
Electric Discharge Coating an alternate process for surface modification/alloying/coating to improve the mechanical and metallurgical properties of the materials using conventional Electrical Discharge Machine. The compaction pressure of semi-sintered nickel and tungsten electrode influences the material migration together with substrate material and pyrolysis carbon results in metal matrix composition coating. In depended of pressure spark gap are stable increases the deposition of alloying materials lessens the formation carbon layer, cracks, voids, blowhole over the surface and made the layer to be metallurgical mixed composition surface that reduces the brittleness. This makes the layer four times higher in hardness value than the substrate material to 1100HV0.5 and reduction in specific wear to 0.082x10-5mm3/Nm depends on the inclusion of alloying material with carbon percentage consequences in self-lubricant properties that varies the wear rate. Surfaces topography obtained during alloying, material migration, mechanism is characterized through Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX)and wear through pin-on-disc tribometer
Since it is difficult to obtain 3D micro-electrodes, simple micro-electrodes with round or rectangular cross-sections are used when performing layer-by-layer scanning EDM to machine 3D micro-structures. This process can process 3D micro-structure, which has deficiencies of complicated technical process and low processing efficiency. In the study, copper was used to fabricate 3D micro-electrodes by micro-milling. Using a reciprocating processing method, micro-EDM was conducted with the 3D micro-electrodes to obtain 3D micro-structures. This method had the advantages of high processing efficiency and a simple technical process. The above work is the main content and novelty of this paper. The paper detailedly studied the effects of the stand-off distance and flushing quantity of dielectric fluid on the machining quality of 3D micro-structure. Furthermore, the effects of rough machining and finish machining on the machined surface were also analyzed. Finally, with flushing quantity of 0.3 L/min, stand-off distance of 300 μm, the 3D micro-structures with 5 μm dimensional error were machined in 304# stainless steel by applying 3D micro-electrodes in micro-EDM, which had good processing efficiency and processing accuracy.
Many studies have carried out on the characteristics of surfaces processed by PMEDM with various powders. However, limited works have used the tungsten carbide powder in the PMEDM process and investigated its effects on the surface properties. In this research, the influence of main process parameters, including the peak current (Ip), the pulse on time (Ton), and the powder concentration (Cp) on surface properties—i.e., surface roughness (Ra), microhardness of surfaces (HV), and surface morphology of SKD61 steel machined by PMEDM with tungsten carbide powder, was explored in two modes: the fine-finish mode and the semi-finish mode. The results show that the peak current, the pulse on time, and the powder concentration have a noticeable influence on surface properties. The surface roughness, the microhardness of surfaces, and the surface morphology at the small peak current (Ip =1 A) and the short pulse on time (Ton =16 µs) were improved better than those at the large peak current (Ip=4 A) and the long pulse on time (Ton =200 µs) with all powder concentrations. The best improvement of the surface roughness at Ip=1 A; Ton=16 μs; Cp=40 g/l is 0.471 ± 0.011µm with a reduction of 57.984% as compared to the normal EDM. The set of processing parameters {Ip=1 A; Ton=16 μs; Cp=60 g/l} has the most positive effect on the improvement of microhardness and surface morphology: The microhardness was enhanced up to 825 ± 19 HV with an increase of 129.167% as compared to the normal EDM. The surface morphology had the smooth surface, the few micro-cracks, the few voids, the few droplets, and the few globules of debris as compared to that of other process parameters and the normal EDM.
Titanium and its alloys are drawing substantial interest of researches owing to high strength at high temperature, excellent corrosion, fracture, resistance, high strength-weight ratio and biological compatibility. The micro parts have huge demands from a size in the range of ten microns to nine hundred microns in different industries. In this work, efforts have been made to review the different research work and effect of various input parameter on performance measures during micro-machining of Titanium alloy is
reported. The work also reports in respective of the surface characterization of micro electric discharge machined surface through XRD and EDS analysis.
